More info needed before anyone can even hazard a guess..
IE: engine stalls or looses all electrical power?
What's been done to it? IE: tune up, filters, fuel system flushed, etc.
When does it do it? Sitting at idle for 30 minutes, driving for 30 minutes, highway, city, etc....
Fuel condition? IE: full tank, almost empty, old fuel, new fuel, etc.
Sounds heat related if it will run for 30 minutes and stall/die.
likely causes: Vapor lock, overheated electrical component, etc.
But that is a pure WAG without more info.
You're lucky your mechanical fuel pump still works after sitting 10 years. The diaphragm usually rots out and makes the pump useless. That's what happened to my 83 when it sat for a couple years. I cured it by yanking the 3.8/c5 out for a 302/T5.....